Hi all,

I bought a '66 Dart (225 w/ automatic) a few month back, but just the other day while getting on the freeway I noticed something I hadn't before. I believe I experienced 4 gears instead of the expected 3 that I thought I had. I did a bit of reading and found out there were a run of A833 4-speeds installed on some(?) A-body's from '64-'66. A bit more reading and I found out that there was another run of A833's that had O.D. and I got a little excited.

So now for the questions...

1) How can I verify that I have an A833 (casting numbers, visual characteristics, etc)?

2) If indeed I have an early A833, what is the cheapest/quickest way to convert to O.D.? Do I need to do a full transmission swap, or are the two transmissions similar enough to swap a few parts or gears around?

A 66 Dart came from the factory with a 904 3 speed auto trans (if auto), or a non syncronized 1st gear 3 speed manual trans (not sure of the number), or a 4 speed manual trans (A-833) non over drive. The A833OD was not untill the later years. There are only two "basic"Chrysler RWD auto OD transmissions, the A-500 which is based on the 904, and the A-518 which is based on the 727. Neither of theses transmissions is an easy conversion, in a 66 Dart or any "A" body slant six car, but it has been done.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

The parts don't really "swap around". You'll be purchasing an A-833 OD and swapping it i with an A-833OD bellhousing, everything else can remain the same if you have an A-833... You'll find the A-833 is a nicer transmission with less rpm loss on upshifts than the OD version...Read the 4 speed article in our articles section to see if your tranny looks like either one.

If you have an automatic and someone has swapped in a later A-904 with the lock up convertor, I've had a few people swear they have a 4th gear, because the lock up applies and to some people it feels like the tranny "shifted"...

-D.Idiot

Thanks for the great insights guys. I do have another question though.

I've seen lots of discussion on different transmission swaps (T5, A-500/518, etc). What is the cheapest/easiest route? Will an A-500 simply bolt on, I've also heard the T5 is nearly a bolt on option (minus the bellhousing and possibly a few something things)?

None of those transmissions you listed bolt in. An A833OD, if you have all the pieces, is easier than any overdrive automatic and easier than any other overdrive manual. If you want a T5 you'll need to know how to weld.

I had a '66 Dart and swapped in an A833OD. It was a lot of work to go from an automatic to a manual. Lots of parts from many sources was a big pain. I later switched it for a standard A833.

What is the goal here? Why do you want overdrive?

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Joshua

The goal is better gas millage and I don't enjoy reving my engine so high while doing normal freeway driving (60-70mph).

Also, sorry for my transmission ignorance, I only have a bit of understanding from what I have read over the past couple weeks. I'm actually an engine and electrical guy so sorry if I end up asking the wrong questions or ones that don't make sense.

It will take a very, very long time to repay the investment in an overdrive transmission. You are not going to hurt the engine at 70 MPH with any gear the factory installed. You are much better off tuning the car carefully and upgrading to electronic ignition. After that a larger exhaust system is a good investment for both power and economy.

_________________
Joshua

Check your rear-end gear. If its reving too high maybe a ring and pinion swap might solve all your problems.

Example.........if you have a 355 gear back there a switch to a 276 would make a big big difference as far as rpms on the hwy.
regards,
MaX

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1966 barracuda 360
1964 signet conv. 170 turbo
Bonneville or Bust 2012

i know this thread is several years old, but i feel like my findings should be here, since they go against what the majority of posters have to say about it.
i had a '63 valiant signet that someone had super-sixed (factory F-body-era 2bbl set-up), and installed an A833OD transmission to.
i would get mid-20's highway, and i had plenty of torque for around town.
i loved this car so much that i am setting up my '65 dart wagon the same way, but better:
*freshened stock 225
*2bbl super-six set-up, complete with 2-1/4" exhaust (possibly dutras)
*mopar (or other) electronic ignition
*8-3/4 sure-grip axle and 10" drums from a '66 dart GT, 3.23
*A833OD trans from a '78 aspen
*4-piston KH disk front brakes from a '72 scamp
upon research, i have read that folks who did this set-up sans the super-six had problems powering their vehicle in OD gear. i'm therefor guessing that a 170 would fall completely flat in .73 4th gear. the added HP gain from the 2bbl set-up on a 225 is perfect for highway cruising. that was evident on my signet--that car sailed effortlessly at 75-80 mph, revved low, and got excellent gas milage.
the added bonus is that it's fun to drive (i have an A903 manual on the column, which can be arduous).
since i have just finished collecting my parts, i can tell you that it is a hefty investment (though the 8-3/4 and front disks are a huge part of the final figure, which really is just frosting on the cake). i suggest only doing this if you are going to keep the car for a while. labor will be extensive. however, IMHO, this is the perfect low-tech set-up for the middle ground between performance and economy. plus, the 4-speed is just plain fun to drive.
eventually, i may wind up experimenting and possibly running an injected turbo-charged motor in mine, but that's a long way off.

Here's the rub....

The big obstacle is making all the parts work together... this means, cam, compression, timing, transmission, rear ratio, tire size....

The key to an OD transmission is to make sure that the prime torque band of the engine build (camshaft, timing, compression) coincides with the rpm for the task the vehicle is being calibrated for (cruise rpm at
highway speeds, drag race high rpm, low torque).

The A-833OD is a balance of love and hate.... on the plus side, the manual transmission is more tolerant of
radical camshafts and higher compression, the OD allows for much nicer rear end ratios for smaller engines
to be streetable for mileage and regular driving... on the other end, the wide ratio between the gears has a
very marked rpm drop on the upshift that can easily knock the rpm out of the power band and make things
'sluggish' or less than desireable (in some cases if the carburator isn't calibrated to be in the mains at this lower rpm at cruise, you will start sacrificing valves, seats, pistons, etc....)... also if you should decide
to leave the clutch out while coasting downhill... with the carb throttle plates shut and the high load on the engine, that carb will be in the idle circuit and go really lean and if not set up correct... you will start 'shooting ducks' (backfire due to lean out), which isn't good for your engine....


The 225 has a really nice 'fat' flat torque band and can mostly tolerate the rpm drop and if the carb is calibrated correctly can also handle bumping along at 15-1700 rpm... The 170 might be a bit more 'peaky' and due to lack of stroke not as much low end torque (a bit less displacement may also equate to a bit less of HP as well, but that is to be expected)....


To help this you will need to raise the rear axle ratio... but how much to raise will depend on the engine build. If you are just adding a super six to a 170 and not changing the cam, the shift of the torque peak
and added lb/ft will be slight... (this can be estimated via a well programmed engine dyno program, some work with a G-tech on a level back road, or most accurately a visit to a dyno facility which is $$$, but
some community colleges have a dyno for testing for emissions, and if your build isn't over 200 HP, and you can make a buddy.. you might be able to test it for much less $).

Being that your vehicles are very light compared to the late A-body, you can easily help the engine out by switching to a 3.55 rear ratio (2.56 final ratio in OD).... or even a 3.91 (2.85 final ratio in OD.. which lies between the stock 3 speed with a 2.76 or 2.94 stock rear ratio)... but because of the steep first gear ratio of 3.09, the 3.55 will be much nicer than the 3.91+ which will be annoying about 10-15 mph... if available for your rearend... you may split the difference if a 3.73 is available....

There are a number of gear ratio spreadsheets on the web you can use to check your transmission ratios vs. tire size and see where the rpm lies at certain MPH. This also can help determine if the cruise rpm will coincide with the calibration of the carburator (mains typically start at 2000 rpm... but vary by calibration... i.e. the feather duster Holley 1945 tends to prefer the mains at a much lower rpm due to the OD+2.94 rear ratio and tall 195/75/14 tires)

Good luck, you are entering the area where seat of the pants gives way to Engineering/Math/Science of your car....



-D.Idiot